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Wednesday, 19 October 2011

Invented in the United States in 1878 the combination square is a very versatile instrument indeed. I thought it might be fun to run through as many ways to use one as I can think of and then see if anyone can come up with any others.

As well as the obvious uses for marking lines square to or at 45 degrees to an edge, the combination square can also be used as a depth gauge:

A rudimentary marking gauge or panel gauge:

A protractor, dovetail marker or an extra sliding bevel if need be:

A graduated centre finder for both establishing and measuring from the centres of round materials:

Or a mitre gauge:

A small level, (and because it's a square you also have a means of gauging for plumb):

A greater level of accuracy can often be achieved by using the components independantly.

The square head can be used as an internal 135 and 90 degree square:

The centre finder as an external 90 degree square (note the cutout for the corner to rest in):

And the protractor head can be used as either a level or an inclinometer:

On a good one like this Moore & Wright 520, the anti glare rule is 2.2mm thick and the sides are precision ground so it is accurate enough to use as a straight edge too:

In almost all cases a dedicated tool probably will do a better job (assuming that you are looking at a similar quality level). However, for a lot of woodworking tasks the level of accuracy you can achieve with a decent combi square is perfectly acceptable.

If budgetary restrictions are a consideration then you may be better off getting one good quality combination set than struggling with lower quality individual tools.

The sheer abundance of things that you can do with a decent combination square make it a wise investment for the beginner and it will always be a useful tool to grab whether you are working in or away from the workshop.

If anyone can come up with any other ways to use combination squares, please feel free to share them.